Komatsu SK09J-2(S/N SK09JF20001-Up)
Komatsuwheel loadersmall ( - wa120 / sk*)

Komatsu SK09J-2(S/N SK09JF20001-Up)

Maintenance schedule, common problems & OEM parts breakdown

The Komatsu SK09J-2 is a wheeled skid steer loader manufactured from 1999 to 2003. It is powered by a 4D98E-1FD engine producing 69.8 hp gross power with a 202.5 cu in displacement. The machine has an operating weight of 3.4 tons (3,400 kg) and a rated operating capacity of 870 kg. It features a 0.45 m³ bucket capacity and a 13.3 gal hydraulic system fluid capacity. The SK09J-2 succeeded the SK09J series (1997-1999) and was succeeded by the SK818-5 and SK1020-5 Turbo models. Configurations offered include standard joystick controls and various attachment packages for material handling, road work, and demolition.

The SK09J-2 introduced a new-generation Komatsu engine designed for high power, low fuel consumption, and reduced emissions compared to its predecessor. It features a sophisticated sensor system that disables machine movement if incorrect operations are detected, enhancing safety in restricted spaces. The machine remains relevant in the used market due to its compact size, excellent visibility, and ease of maintenance access.

Below: full specifications, fluids & capacities, the factory service schedule, common service parts, verified fault codes, what owners discuss, attachment guidance, the complete assembly directory, and a serial-number reference. Complete parts lists with full OEM part numbers, exploded diagrams, quantities, and fitment data are available free in Heavy Parts AI.

Komatsu SK09J-2(S/N SK09JF20001-Up) specifications

Engine

Model4D98E-1FD
Number of Cylinders4
Displacement202.5 cu in (3,318 cm³)
Gross Power69.8 hp (52.1 kW) @ 2,300 rpm
Net Power67.1 hp (50 kW) @ 2,300 rpm

Weights

Operating Weight7,495.8 lb (3,400 kg)
Rated Operating Capacity1,918.1 lb (870 kg)

Dimensions

Transport Length (with bucket)11.09 ft (3.38 m)
Transport Width (over tires)5.66 ft (1.75 m)
Transport Height (to top of cab)7.38 ft (2.25 m)
Wheelbase3.28 ft (1.00 m)
Ground Clearance9.45 in (240 mm)
Clearance at Max Lift and Dump7.88 ft (2.40 m)
Reach at Max Lift and Dump25.79 in (655 mm)
Turning Radius (from center, machine rear)63.39 in (1,610 mm)
Turning Radius (from center, inc bucket)80.79 in (2,050 mm)
Tipping Angle3,836.1 degrees

Performance

Max Travel Speed8.1 mph (13 km/h)
Operating Speed5 mph (8 km/h)
Breakout Force5,401.4 lb (2,400 kgf)
Bucket Capacity0.1 cu yd (0.45 m³)

Service capacities (summary)

Fuel Tank21.2 gal (80 L)
Hydraulic System13.3 gal (50 L)
Engine Oil2.4 gal (9 L)

Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.

Komatsu SK09J-2(S/N SK09JF20001-Up) maintenance schedule

Service intervalTasks
Every 10 h
  • Check engine oil level and condition.
  • Check hydraulic fluid level at sight glass.
  • Check coolant level and ensure cap is secure.
  • Check fuel level and drain water from separator.
  • Check DEF level on Tier 4 machines.
  • Inspect air filter restriction indicator.
  • Check tire condition and inflation pressure.
  • Inspect hydraulic hoses for cracks or leaks.
  • Check pins, bushings, and attachment points.
  • Clear debris from radiator and oil cooler fins.
  • Check for fluid leaks under the machine.
  • Verify ROPS/FOPS integrity and seat belt condition.
  • Test horn, backup alarm, and lights.
  • Ensure emergency shutoff is accessible.
  • Start engine and verify gauges and KOMTRAX display are normal.
  • Test all controls for smooth response.
  • Check service and parking brakes.
Every 250 h
  • Change engine oil and filter.
  • Grease all points including bucket, Z-bar/linkage, steering, and axle.
  • Check fluid levels.
  • Check air filter outer element.
  • Inspect belts, hoses, and clamps.
  • Perform visual walk-around inspection.
Every 500 h
  • Replace fuel filter and drain water separator.
  • Replace hydraulic return filter.
  • Perform battery service and load test.
  • Test coolant SCA concentration.
  • Collect KOWA oil sample.
  • Perform detailed undercarriage inspection.
Every 1,000 h
  • Collect hydraulic oil sample.
  • Change final drive oil.
  • Inspect turbocharger.
  • Perform wear measurements on linkage and pins.
  • Check valve adjustment.
  • Perform structural inspection of frame and welds.
Every 2,000 h
  • Change hydraulic oil.
  • Flush and replace coolant.
  • Change transmission oil and filter.
  • Change axle oil (front and rear).
  • Change differential oil.
  • Perform comprehensive component evaluation.

Servicing the SK09J-2(S/N SK09JF20001-Up) beyond the schedule

Predictive Maintenance & Fluid Analysis

Utilize KOWA fluid analysis at every 500-hour interval to monitor engine wear metals and hydraulic contamination. Check the air filter restriction indicator daily and clean the outer element at 250 hours. Monitor the coolant SCA concentration at 500 hours to prevent liner cavitation. Inspect the hydraulic return filter at 500 hours to protect sensitive valve components. Verify the DEF level regularly on Tier 4 compliant units to ensure proper emissions system function. Track KOMTRAX telematics data for load frequency and fault codes to anticipate component stress before failure occurs.

Corrective & Common Repairs

Address hydraulic hose leaks immediately, as high-pressure lines are prone to abrasion against the frame. Replace the fuel filter and drain the water separator at 500 hours to prevent injector damage. Inspect the 4D98E-1FD engine belts and clamps at 250 hours for cracking or looseness. Check the articulation and steering pins for play and grease them frequently to prevent chassis binding. Inspect the tire condition and inflation pressure daily to ensure stable handling and prevent premature wear on the axle seals. Replace worn bucket teeth and cutting edges to maintain the 5,401.4 lb breakout force efficiency.

Overhaul & Rebuild Points

Perform a comprehensive component evaluation at 2,000 hours, including a hydraulic oil change and transmission service. Change the final drive oil at 1,000 hours and inspect the turbocharger for wear. At 2,000 hours, change the axle oil and differential oil to prevent gear wear. Inspect the structural frame and welds for fatigue cracks during the 1,000-hour structural inspection. Evaluate the battery health and alternator output at 500 hours to ensure reliable starting. Measure wear on the Z-bar linkage and pivot points to determine if bushing replacement is required to restore geometry.

Seasonal & Environment Servicing

Clear debris from the radiator and oil cooler fins daily to prevent overheating in dusty or hot environments. Check the coolant level and cap security before every shift to maintain thermal regulation. In cold weather, ensure the DEF system is protected and the fuel water separator is drained frequently to prevent gelling. Inspect the hydraulic hoses for brittleness in extreme cold and replace if necessary. Verify the battery charge state in low temperatures to ensure reliable starts. Adjust tire pressure according to terrain conditions to optimize traction and reduce ground pressure on soft surfaces.

SK09J-2(S/N SK09JF20001-Up) common service parts

Part numberPart
YM102103-55520O-Ring,(For Fuel Filter)Check fitment →
YM129470-55610Body, Fuel FilterCheck fitment →
848001079Air Filter, AssemblyCheck fitment →
885141126Glass, Transmission Oil Filter CloggingCheck fitment →
YM121850-55710ElementCheck fitment →

Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.

SK09J-2(S/N SK09JF20001-Up) fault codes & troubleshooting

CodeMeaningLikely causeWhat to do
E10Engine controller power failureECM power connections, fuses, or ground wires are faultyInspect ECM power connections, fuses, or ground wires
CA115Engine crankshaft speed sensor failureBroken sensor, wiring issue, or connector corrosionReplace the speed sensor, and verify the voltage at the pin connector
CA441Battery voltage too lowAlternator or battery failure; voltage regulator issueReplace the alternator or battery; check the voltage regulator
CA442Battery voltage too highAlternator or battery failure; voltage regulator issueReplace the alternator or battery; check the voltage regulator
AA10NXAir cleaner cloggingDirty or blocked air filter elementReplace the air filter
B@BCNSEngine coolant overheatingRadiator fins blocked, fan belt failure, or low coolant levelCheck radiator fins, fan belt, and coolant level
B@HANSHydraulic oil overheatingDirty hydraulic filter, low oil level, or cooler fan failureChange hydraulic filter and oil; check cooler fan
AB00KECharge voltage lowAlternator failure or loose beltReplace the alternator or tighten the belt

Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.

SK09J-2(S/N SK09JF20001-Up) attachments & work tools

Standard Buckets

The Komatsu SK09J-2 is equipped with a standard bucket having a capacity of 0.45 m³ (0.59 yd³). The machine has a rated operating capacity of 870 kg (1918 lb) and an operating weight of 3.4 t (7496 lb). The breakout force is 5401.4 lb (24.0 kN). Bucket sizes vary by configuration/series.

Coupler Systems

The machine utilizes a standard skid steer quick-attach coupler system for tool interchange. Factory specifications for the SK09J-2 do not list specific aftermarket coupler part numbers, but the frame is designed for standard industry-compatible mounting interfaces.

Hydraulic Kits & Auxiliaries

An auxiliary hydraulic kit is available for the SK09J-2, including a control pedal for superflow operation. The hydraulic system fluid capacity is 13.3 gal (50.4 L). Specific hydraulic kit configurations vary by machine serial number and dealer options.

Engine & Fluids

The SK09J-2 uses a 4D98E-1FD engine with 69.8 hp (50 kW) gross power. Komatsu recommends Komatsu Genuine Lubricants, including specific diesel engine oil, hydraulic oil, and super-coolant AF-NAC for optimal performance and component life.

All SK09J-2(S/N SK09JF20001-Up) assemblies by section

Every catalogued assembly group for the Komatsu SK09J-2(S/N SK09JF20001-Up). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Control System
Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Control System : Auxiliary Hydraulic Kit Control Pedal
20***00Pedal2
33***64Handle1
33***12Yoke1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Control System : Auxiliary Hydraulic Kit Control Pedal (Superflow)
20***00Pedal2
33***64Handle1
33***12Yoke1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Control System : Fuel Control Lever
20***00Pedal1
33***78Support1
33***64Plate1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Control System : L.H. Servocontrol
33***79Tee2
33***81Elbow2
39***62Hose4
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Control System : R.H. Servocontrol
39***89Hose2
39***90Hose2
3K***00Protection2
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Control System : Safety Bars
33***28Bushing2
33***66Plate R.H1
33***67Plate L.H1
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Engine
Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Air Intake Manifold
YM***02Screw2
YM***00Manifold,Air Intake1
YM***21Gasket (Kit)1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Camshaft And Driving Gear
YM***00Idle Gear Ass'Y1
YM***00Tappet Rod8
YM***00Gear Ass'Y,Hydraulic Pump1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Cooling Water System
YM***50V-Belt1
YM***90Valve,Water Drain1
YM***02Screw3
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Crankshaft And Piston
YM***50Ring Set (+0.25 mm)4
YM***00Crankshaft, Assembly1
YM***80Flywheel, Assembly1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Cylinder Block
YM***60Cylinder Block, Assembly1
YM***00Screw18
YM***00Main Metal Ass'Y (Std)5
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Cylinder Head
87***29Motor, Assembly1
YM***80Retainer, Spring8
YM***40Seal,Valve? Exhaust (Kit)4
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Electrical System
YM***41Cover, Rear1
YM***50Cable1
YM***80Pulley1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Engine Stop Device
YM***00Pin, Cotter1
YM***02Nut1
YM***11Coil, Assembly1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Exhaust Manifold
YM***02Nut2
YM***01Gasket (Kit)1
YM***52Screw6
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Feed Pump
YM***40Gasket4
YM***60O-Ring2
YM***00Screw1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Flywheel - Lubricating Oil Sump
YM***52Screw9
YM***10Oil Sump1
YM***20Housing, Flywheel1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Fuel Injection Line
YM***02Bolt Plated1
YM***50Nozzle4
YM***40Injection Pipe N. 41
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Fuel Injection Pump
YM***00Segment4
YM***00Gasket Disc4
YM***20Valve,Delivery4
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Fuel Piping
YM***02Screw1
YM***10Protector1
YM***80Screw1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Gasket Set
YM***40Seal,Valve? Exhaust (Kit)1
YM***00O-Ring (Kit)1
YM***01Gasket (Kit)1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Gear Housing
YM***02Bolt Plated3
YM***51Cap, Lub. Oil Supply1
YM***02Screw10
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Governor
YM***40Screw2
YM***00Nut1
YM***00Screw1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Lubricating Oil System
YM***40Stud1
YM***81Retainer1
YM***00O-Ring (Kit)1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine : Starter Motor
YM***80Holder Brush, Assembly1
YM***10Retainer1
YM***20Shift Lever Ass'Y1
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Engine Related Parts And Electrical System
Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine Related Parts And Electrical System : Air Cleaner And Mounting
33***74Support1
33***80Pipe1
33***48Terminal1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine Related Parts And Electrical System : Battery
30***14Retainer1
33***52Support1
50***07Rubber1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine Related Parts And Electrical System : Dashboard
33***12Dashboard1
3F***05Plate, Ignition Panel1
80***60Screw4
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine Related Parts And Electrical System : Electrical System (1/3)
80***86Washer1
80***01Spring Washer (With Stabilizers Only)1
80***34Collar1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine Related Parts And Electrical System : Electrical System (2/3)
33***60Wiring Harness1
33***05Protection1
80***41Bolt4
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine Related Parts And Electrical System : Electrical System (3/3)
80***66Bolt2
80***86Washer1
80***00Washer (For Homologation Road)2
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine Related Parts And Electrical System : Engine Mounting Parts
33***75Support, Front, L.H1
33***76Support, Front, R.H1
33***58Support, Rear, L.H1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine Related Parts And Electrical System : Fuel Piping
33***70Hose1
3F***04Protection1
3F***05Protection1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine Related Parts And Electrical System : Fuel Tank
20***57Plug, Assembly1
31***58Cover1
33***52Float1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine Related Parts And Electrical System : Muffler And Piping
33***56Pipe, Upper1
33***77Pipe, Upper1
33***78Muffler1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine Related Parts And Electrical System : Power Take Off
33***16Washer2
33***53Support1
33***81Cover1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine Related Parts And Electrical System : Radiator (1/2)
20***87Support, Tank1
33***85Protection1
33***64Sleeve1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Engine Related Parts And Electrical System : Radiator (2/2)
Frame
Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Frame : Frame
20***20Plug2
20***80Ballast2
33***68Shim2
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Frame : Hydraulic Piping (Parking Brake Line)
33***81Cock, Assembly1
33***11Union1
39***21Hose1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Frame : Hydraulic Piping (Parking Brake Line) (For Road Circulation)
33***81Cock, Assembly1
33***00Block1
33***11Union1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Frame : Transmission
20***90Crown Wheel2
33***07Washer2
33***09Link2
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Frame : Wheels
11***77Wheel, Assembly1
11***79Wheel, Assembly4
33***11Column12
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Guard And Operator'S Cab
Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Guard And Operator'S Cab : Cabin (1/2)
33***10Gasket, R.H1
33***11Gasket, L.H1
33***61Protection1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Guard And Operator'S Cab : Cabin (2/2)
33***27Spacer (For Mounting Safety Valves)1
33***79Retainer1
33***53Box1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Guard And Operator'S Cab : Engine Hood
33***52Support1
33***53Striker1
33***02Spring1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Guard And Operator'S Cab : Front Door
33***53Wiper, Assembly1
33***54Door, Assembly1
33***55Bracket2
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Guard And Operator'S Cab : Heating System
33***16Diffuser1
33***50Support1
33***51Support1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Guard And Operator'S Cab : Inner Cabin Cover
33***45Sheet1
33***02Cover1
33***16Sheet1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Guard And Operator'S Cab : Operator'S Cab (Equipment) (Only For Germany)
80***04Nut6
80***08Washer (Optional)4
80***09Washer2
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Guard And Operator'S Cab : Operator'S Seat
33***63Seat Belt, Assembly1
33***68Washer4
33***22Plate (Except Germany)1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Guard And Operator'S Cab : Operator'S Seat (Optional)
33***63Seat Belt, Assembly1
33***68Washer4
80***88Bolt (With Stabilizers Only)4
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Guard And Operator'S Cab : Ppc Valves Support
33***70Guide, R.H1
33***71Guide, L.H1
33***74Support, L.H1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Guard And Operator'S Cab : Rear Hood
33***54Hinge2
33***13Pin2
33***67Pushrod1
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Mark Plate
Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Mark Plate : Equipment (For Road Circulation)
20***24Chain (With Stabilizers Only)2
33***23Plate, L.H1
33***24Plate, R.H1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Mark Plate : Equipment (For Road Circulation) (Cold Planner Version)
33***50Spacer2
33***51Pin2
50***92Stopper1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Mark Plate : Equipment (For Road Circulation) (Germany Version)
20***24Chain (With Stabilizers Only)2
33***23Plate, L.H1
33***24Plate, R.H1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Mark Plate : Equipment (Germany Version)
Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Mark Plate : Tools
33***35Support1
33***53V-Belt1
33***54Tools Bag1
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Work Equipment
Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment : Arm
33***53V-Belt1
33***50Arm1
33***51Safety Bar1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment : Bucket
20***42Handle1
33***06Spacer6
33***18Link1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment : Bucket Tipping Cylinder (L.H.)
39***49Bushing1
39***52Bushing1
39***13Dump Cylinder, L.H1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment : Bucket Tipping Cylinder (R.H.)
39***49Bushing1
39***52Bushing1
39***14Dump Cylinder, R.H1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment : Lifting Cylinder : Unit_02_of_02
39***30Bushing1
39***52Bushing1
39***09Lift Cylinder, L.H1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment : Lifting Cylinder : Unit_01_of_02
39***30Bushing1
39***52Bushing1
39***08Lift Cylinder, R.H1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment : Stabilizer Foot
33***51L.H. Stabilizator Foot1
33***52R.H. Stabilizator Foot1
33***55L.H. Cylinder, Assembly1
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Work Equipment Control System
Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Bucket Lifting Hydraulic System (Floating Version)
33***02Block1
39***98Hose1
39***72Hose2
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Cold Plenner Return Kit
20***53Body (For Hand Hammer)1
20***62Plug (For Hand Hammer)1
20***06Clamp (For Hand Hammer)1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Control Valve (1/2) : Unit_02_of_02
80***77Screw8
84***50Element, Assembly1
84***52Element, Assembly1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Control Valve (1/2) : Unit_01_of_02
80***77Screw4
84***69Tie-Rod, Assembly4
84***70Kit, Gasket (Control Valve, Assembly.)1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Control Valve (For Outrigger)
80***77Screw4
84***50Element, Assembly2
84***67Tie-Rod, Assembly4
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Final Drive (1/2)
80***49Screw2
84***12Hydraulic Motor1
84***73Spring11
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Final Drive (2/2)
80***74Screw2
84***09Plug2
84***40Cap Valve1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Auxiliary Kit Line)
20***48Coupling, Assembly. (For Hammer On Plate And On Excavator)1
20***49Fitting (For Hammer On Plate And On Excavator)1
20***50Body (For Hammer On Plate And On Excavator)1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Bucket Lifting Cylinder)
20***70Clamp4
30***22Clamp2
33***55Pipe1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Bucket Tipping Cylinder)
33***15Retainer1
33***51Pipe1
33***52Pipe1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Cold Planner Kit)
20***40Union1
20***58Fitting1
20***61Plug1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Oil Cooler And Return Line)
20***49Union1
20***30Plug1
20***06Union1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Suction And Delivery Line)
20***90Pressure Take-Up1
33***84Union1
33***88Pipe1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Suction And Delivery Line) (Superflow)
33***03Plate1
39***60Hose2
39***30Hose1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Travel Line) (1/2)
33***81Pipe1
33***86Union2
39***67Hose1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Travel Line) (2/2)
33***67Pipe1
33***77Elbow4
33***78Union1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Hydraulic Piping (Travel Line) (2/2) (For Road Circulation)
33***67Pipe1
33***77Elbow4
33***78Union1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Hydraulic Piping L.H. (Servocontrol Line)
33***11Union1
39***42Hose1
39***63Hose1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Hydraulic Piping R.H. (Servocontrol Line)
39***92Hose1
39***65Hose1
50***44Union1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Hydraulic Piping R.H. (Servocontrol Line) (For Road Circulation)
33***53Link (For Homologation Road)1
39***92Hose1
39***65Hose1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Hydraulic Pump (1/2)
84***10Pump, Assembly1
84***30Pump, Assembly1
84***57Pin1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Hydraulic Pump (2/2)
Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Hydraulic Tank
20***90Plug1
20***40Indicator Oil Level1
33***54Hydraulic Tank1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Outrigger Control Lever (1/2)
33***12Union1
39***57Hose2
39***65Hose1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Outrigger Control Lever (2/2)
33***50Pipe2
33***52Pipe1
33***53Pipe1
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Ppc Valve, L.H.
84***57Ppc Valve, L.H., Assembly1
84***52Washer8
84***56Shim, 0.100 mm0
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Ppc Valve, R.H.
84***52Washer8
84***56Shim, 0.100 mm0
84***57Shim, 0.200 mm0
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Komatsu : Sk09j-2(S/N Sk09jf20001-Up) : Work Equipment Control System : Self-Levelling Valve
84***25Valve1
84***26O-Ring2
84***27Plug2
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SK09J-2(S/N SK09JF20001-Up) serial number reference

The PIN plate is riveted to the rear hydraulic column on the right side of the machine (as seen from the direction of travel). Read the first four characters of the serial number on the plate to identify the prefix (e.g., SK09JF).

PrefixIdentifies
SK09JFSK09J-2

Frequently asked questions

What engine does the Komatsu SK09J-2 use?

The Komatsu SK09J-2 is equipped with a 4D98E-1FD engine producing 69.8 hp gross power with a 202.5 cu in displacement.

What is the operating weight of the Komatsu SK09J-2?

The operating weight is 3.4 tons (3,400 kg), varying slightly by configuration and attachment package.

What model replaced the Komatsu SK09J-2?

The SK09J-2 was succeeded by the SK818-5 and SK1020-5 Turbo models in Komatsu's wheeled skid steer lineup.

What SK09J-2(S/N SK09JF20001-Up) owners discuss

What engine powers the Komatsu SK09J-2 (S/N SK09JF20001-Up) and what are its key specifications?
The Komatsu SK09J-2 (S/N SK09JF20001-Up) is equipped with a Komatsu 4D98E-1FD engine. This engine delivers 69.8 hp (gross power) with a total cylinder displacement of 202.5 cu in. The machine has a fuel capacity of 21.2 gal and a hydraulic system fluid capacity of 13.3 gal. The operating weight is 7,495.8 lb (3.4 tons), and the rated operating capacity is 870 kg (1,918.1 lb). The breakout force is 5,401.4 lb, and the tipping load angle is 3,836.1 degrees. The transport length is 3.21 m (11.09 ft with bucket), width is 1.75 m (5.74 ft), and height is 2.25 m (7.38 ft). Travel speed is 13 km/h (8.1 mph). Bucket capacity is 0.45 m³ (0.59 cu yd). Note: The SK09J-1 (S/N SK09JF20001-Up) is a distinct prior generation; ensure the serial prefix matches the SK09J-2 specification sheet. Fluid specifications include Komatsu Diesel Engine Oil, Komatsu Hydraulic Oil HO, and Komatsu Axle Oil AXO80. Super-coolant AF-NAC is specified for the cooling system. Have your dealer verify the exact engine serial and emission tier for your specific unit before purchase.
What are the common hydraulic behaviors and issues reported for the Komatsu SK09J-2?
Operators note that the SK09J-2 hydraulic system can become sluggish when hot due to viscosity loss in older oil or internal pump wear. The machine relies on a closed-center hydraulic system; if all functions slow simultaneously, check the hydraulic oil level, filter condition, and engine RPM under load before assuming pump failure. If only one function is slow, inspect the specific cylinder seals, control valve spools, and pilot lines. The system is sensitive to contamination; regular replacement of hydraulic filters is critical to prevent premature wear of the main control valve and pump components. Ensure the hydraulic oil meets Komatsu HO specifications.
What undercarriage and wear patterns are typical for the Komatsu SK09J-2 skid steer?
The SK09J-2 is a wheeled skid steer, so it does not have a tracked undercarriage. Wear patterns focus on the tires, axle seals, and pivot pins. The machine is noted for being long and less nimble than some competitors, which can lead to uneven tire wear if used extensively in tight turning applications. Axle torque has been reported as average; operators should monitor axle seals for leaks, especially after heavy loading. Loader arms and bucket pins are subject to standard wear; inspect bushings and bearings regularly to prevent excessive play that affects lift capacity and stability. The machine's stability is good on rough terrain due to its wheelbase, but operators should avoid side-loading the tires excessively.
What engine quirks or maintenance items are specific to the 4D98E-1FD series in this machine?
The 4D98E-1FD engine is a compact, reliable unit but requires attention to the cooling system. Overheating can occur if the radiator, hydraulic oil cooler, and charge-air cooler are packed with debris. Clean the spaces between the heat exchangers regularly. The engine is sensitive to fuel quality; use clean diesel and replace fuel filters promptly to prevent injector issues. Engine oil must meet Komatsu Diesel Engine Oil specifications. Check coolant level when cold and inspect for leaks. The engine is designed for low emissions and noise, so ensure the air intake system is sealed to prevent dust ingestion.
What are the common electrical or sensor issues for the Komatsu SK09J-2?
The SK09J-2 features a sophisticated sensor system that disables movement if incorrect operations are detected. Intermittent starting or random shutdowns can be caused by faulty sensors, unstable power supply, or corroded ground connections. Check the battery state of charge and terminal condition. Inspect the main starter cable and starter relay. Dashboard gauges are located on the lap bar; ensure connectors are secure. If multiple fault codes appear, check the battery voltage and ground straps first. The machine uses a selector switch for pattern change (E/H), which can cause issues if not properly maintained; ensure the switch functions correctly to avoid flow imbalances.
What should be checked when buying a used Komatsu SK09J-2 (S/N SK09JF20001-Up)?
When buying a used SK09J-2, verify the serial number starts with SK09JF2 to confirm it is the SK09J-2 model and not the SK09J-1. Check the engine for black smoke under load, which may indicate injector or air filter issues. Test all hydraulic functions cold and hot to detect sluggishness or leaks. Inspect tires for uneven wear and check axle seals for leaks. Verify operation of the pattern selector switch and all safety sensors. Check coolant level and condition. Ensure the machine has been maintained with Komatsu-specified fluids.
What are the recommended fluid specifications for the Komatsu SK09J-2?
The Komatsu SK09J-2 requires specific fluids for optimal performance: use Komatsu Diesel Engine Oil for the engine, Komatsu Hydraulic Oil HO for the hydraulic system, and Komatsu Axle Oil AXO80 for the axles. Use Komatsu Powertrain Oil TO10 or TO30 if applicable to the transmission. Super-coolant AF-NAC is specified for the cooling system.

Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.

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